The European Patent Office (EPO) upheld an amended form of a Harvard University patent on a mouse genetically modified to develop cancer earlier this week. The decision, which limits the patent to mice only, ends a legal battle with environmental groups who had expressed concerns about animal cruelty.

While the 1992 European patent had fully protected the method of genetic manipulation used by John Emory Andrus Professor of Genetics Philip Leder ’56, then-Harvard researcher Timothy Stewart and DuPont, the ruling marks an additional step back from a 2001 decision that restricted it to rodents.

Despite the limitations, Leder welcomed the ruling.

“As a practical matter, it turns out mice have a number of advantages,” he said, listing their 21-day gestation period, intact immune systems and known gene sequence among the benefits.

And while Greenpeace—among the six environmental and animal protection groups that appealed the 2001 ruling—was not entirely satisfied with the decision, the group touted the amendment as a “partial success.”

The group would have liked to see the EPO discontinue its practice of issuing patents for mammals, Greenpeace spokesperson Christoph Then wrote in an e-mail.

This case, he said, was “something of a door opener in general for patents on life—[a] highly crucial and symbolic case.”

Though the patent office recognized the ethical and animal cruelty concerns surrounding its decision, the EPO also pointed to the potential medical uses of the patent as a factor in its ruling.

In 1988, the United States Patent and Trademark Office granted a patent to Leder and Stewart, making “OncoMouse” the first “transgenic non-human mammal” to be patented.

Intended to facilitate cancer research, the OncoMouse has generated considerable controversy, not simply for the patenting of life forms, but also for DuPont’s intellectual property claim to the genetically engineered animal.

But Then said that in Europe protests focus primarily on animal rights concerns, not DuPont’s monopoly on the specific application of the technology.

Leder also noted that the decision could pave the way for advances in the field.

“It means that other animal modifications will be patentable and will encourage people to be creative and to invest in this field of research,” he said.

—Material from the Associated Press was used in the reporting of this article.

—Staff writer Margaret W. Ho can be reached at mwho@fas.harvard.edu.